1. Field of the Invention
The present invention is directed to a method, a computer system and a computer program product for transmitting a print job from a host computer to a print server. It is particularly directed to a method and to a system for processing a print data stream that is edited for output on a printer device. Such an editing typically occurs in computers that process print datafiles or print data from application programs printer-adapted. The print data, for example, are thereby converted in an output stream of a specific print data language such as AFP® (Advanced Function Presentation), PCL or PostScript.
2. Description of the Related Art
In large computer centers, great quantities of print data that comprise up to tens of thousands of pages are typically compiled (in a spooling event) in a host computer (such as a mainframe computer) and print jobs are generated therefrom, the latter being adapted for output on high-performance printer systems such that the high-performance printer systems have an optimum usage factor over time in a production mode. They can thereby be largely utilized in continuous operation. Mainframe computers are often operated with the operating systems OS/390 or z/OS. The largest AFP print jobs are generated worldwide on such mainframe computers.
High-performance printers for processing such gigantic print jobs with printing speeds from approximately 40 DIN A4 pages per minute to more than 1000 DIN A4 pages per minute are described, for example, in the publication Das Druckerbuch, edited by Dr. Gerd Goldmann (Océ Printing Systems GmbH), Edition 6, May 2001, ISBN 3-000-00 1019-X. Chapter 14 (pages 14-1 through 14-20) of this publication describe the server system known by the name of PRISMA PRO® that serves for editing print data stream in production printing environments.
The print data format AFP (Advanced Function Presentation) is described, for example, in the publication No. F-544-3884-01 of IBM Corporation bearing the title “AFP Programming Guide and Line Data Reference”. The specification for a further data stream with the designation “S/370 Line-Mode Data) is also described in this publication. The print data stream AFP was further-developed into the print data stream MO:DCA that is described in the IBM publication SC31-6892-04 bearing the title “Mixed Object Document Content Architecture Reference”. Details of this data stream, particularly the employment of structured fields, are disclosed by U.S. Pat. No. 5,768,488. Below, the print data streams that have just been referenced shall be referred to in simplified fashion as AFP data streams.
For output on a printer system, AFP print data streams are usually converted into a printer-adapted data stream IPDS™ (Intelligent Printer Data Stream). AFP elements that reside at various locations in the AFP data stream or, respectively, derive from various sources are thereby usually merged with the corresponding, variable print data.
The published PCT Patent Application WO 01/77807 A2 discloses a method and a computer system wherein AFP print data is checked and potentially normalized onto a uniform data format, wherein the normalized data is sorted and indexed as needed and wherein, finally, an index datafile, a resource datafile and a datafile with the variable data are output.
U.S. Pat. No. 5,940,584 and Published PCT Patent Application WO 99/12337 A2 disclose methods and systems for archiving print data.
The aforementioned publications and patent applications are herewith incorporated by reference into the present specification.
Due to the relatively expensive computing times of host computers, AFP data are transmitted from the host computer onto a print server platform. As a result thereof, the relatively expensive computing times of the host computer can be saved and the host computer can be relieved of tasks, so that the computing capacity of the host computer is available for other tasks. The possibility of printing at dispersed print locations also favors the use of print severs. Computer programs that run on print servers, further, are often very user-friendly and adapted to a productive employment in optimizing fashion.
AFP print data streams are composed of one or more pages of variable print data, i.e. page-individual print data, and one or more AFP resource data that are provided are required for employment on a plurality of pages in order to be able to print out the AFP print data stream on a printer device. Such resources are, for example, overlay data (overlays), page segments, object contamens or character sets (fonts) as well as formatting elements such as, for example, Formdef and Pagedef.
Printer driver programs are available for the transmission of print data from a mainframe computer to a printer device, for instance the program SPS™ distributed by the assignee, that are not only transfer programs for print data from the spooling event to the printer device but that also comprise further functions that allow an enhancement or, respectively, formatting of print data. With the assistance of what are referred to as Pagedef objects and Formdef objects, positionings can be undertaken, fonts can be selected and pages, segments and overlays can be mixed in. This task can require a CPU performance in the range of 6-8 MIPs. High-performance personal computers (PC) make this computing capacity available for less than one-tenth the costs of a mainframe computer. The outsourcing of this task from the mainframe computer to a PC-based print server is therefore very economical.
Given such an outsourcing, however, the problem often arises that the variable print data and the AFP resource data connected thereto are not all stored in one print datafile but are stored in various datafiles, namely the print data in the spool datafile and the resource data in one or more library datafiles.
A second problem is that AFP resource data are normally used by two or more AFP print applications and are stored in library datafiles without any indication in the library files regarding which applications use which resources.
A third problem is that a fully functional analysis program (such as a AFP parser) is required in order to determine which AFP resources are used by which AFP application because a parsing event at AFP print data is the only way to reliably know which resources the application is using.
Whereas, thus, the variable print data of an AFP print application can be automatically transmitted from a host computer to a print server, for example with the product PSF AFP Download of IBM, the AFP resource data that the AFP print application uses must be separately transmitted. The respective user thereby bears the responsibility that the print server on which the application is printed later has access at the time of printing to the AFP resource data or, respectively, to the libraries that store the resource data.